Formaldehyde-generator.



No. 737,413. PATENTED AUG.I25, 1903. R. W. JOHNSON.

FRMALDEHYDE GENERATOR.

APPLIOATION FILED DB0. 6. 1901.

No MODEL.

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UNTTED STATES Patented August 25, 1903.

PATENT OFFICE.

FORMALDEHYDE-G EN ERATOR.

SPECIFICATION forming part of Letters Patent No. 737,413, dated August25, 1903.

Application led December 6, 1901. Serial No. 84,908. (No model.)

To all whom, t may concern:

Be it known that l, ROBERT W. JOHNSON, a citizen of the United States,residing in the city of New Brunswick, county of Middlesex, State of NewJersey, have invented a certain new and useful Improvement inFormaldehyde-Generators, of which the following is a description.

The object I have in view is to produce aV simple and eifective devicefor producing formaldehyde gas from the solid or polymerized forms offormaldehyde, commercially known as paraform, by combustion in acontainer in which the combustion is restricted and the gas is drivenoft by the heat produced by burning a small portion of the solid.

This device is illustrated in the drawings,

former to give the desired thickness, the.

layers being cemented together by silicate of soda. In this way there isproduced a rectangular tube of the proper length. The top of thecontainer is closed by a capl B, made of a square of perforated sheetmetal of such size that when the corners b of the sheet are turned downon the dotted lines shown in in Fig. 3 the square of smaller size withinthese dotted lines will be that of the side walls of the container. Thiscap is preferably secured to the container by wrapping the points bbetween layers of the asbestos paper of which the side walls A areformed, and the cap may be additionally fixed in position by means ofthe silicate of soda. The mass of paraform is compressed into the formof a cylindrical candle C, which is preferably coated with paraffin toprevent evaporation before use. This candle has a length somewhat lessthan the side walls of the container, and its diameter is equal to thewidth of these side walls, at least at its larger end, Fig. 2, so as totouch such side walls and be held in a central position by them. Thecan; dle is inserted into the container from the bottom until it restsagainst the under side of the cap B. The candle, although touching theside walls of the container, does not en tirely fill the container,because of its cylindrical form, the angular container providingdraft-openings at the angles for permitting combustion of the candle atits lower end and for directing the products of combustion upwardly incontact with the sides of the candle. The candle is held in thecontainer by a bridge-piece D, formed, preferably, of a strip ofperforated metal having a less width than the container and insertedinto the container from the bottom and secured therein .by thesilicate-of-soda cement and also by punching the metal into the asbestoswalls by means of a suitable tool, as shown at d. This bridge-pieceholds the candle firmly in position, so that it will not be injured byshipment, and also forms a support for the candle while burning,preventing it from dropping to the lower end of the container. The lowerend of the container has V-shaped openings a cut into two of the sidewalls, so as to form air-inlets for supporting combustion atthe lowerend of the candle.

In use the candle is lighted at its lower end, and the generator is thenplaced in a shallow dish containing water, which, however,should nothave a depth sufficient to entirely close the air-inlets a. The candleburns at its lower end, to which the combustion is restricted by therestriction ot' the outlet at the top ofthe container, the formaldehydegas produced by the volatilization of the paraform escaping through theperforated cap into the room or space to be fnmigated or disinfected.The water in the dish in which the generator is placed is absorbed bythe asbestos-paper side walls and is drawn by capillary attraction intothe heated zone around the flame at the lower end of the candle, whereit is vaporized and -passing upwardly both inside and outside of thecontainer mingles with the formaldehyde gas and prevents therepolymerization-of the formaldehyde. 1

The asbestos forming the side walls of the container being an effectivenon-conductor of heat conserves the heat produced by the llame at thelower end of the candle and restilts inthe conversion of the paraforminto formaldehyde gas with the minimum loss by combustion. The use ofasbestos paper also for the side walls of the container reduces theexpense of the construction over what it would be if metal wereemployed. The metal parts are simple and inexpensive. The rectangularform of the container is also advantageous, because of the saving ofspace in packing.

l. In aformaldehyde-generator,a container made in the form of a tube ofangular crosssection open at one end andy closed at the other end by aperforated cap, in combination with a candle of cylindrical formtouching the side Walls of the container and held against lateraldisplacement thereby but leaving draft-openings at the angles of thecontainer, substantially as set forth.

2. In a'formaldehyde-generator,a container made in the form of a tube ofangular crosssection open at one end and closed at the other end by aperforated cap, and a bridge-piece connecting the walls of the containernear its open end, in combination with a candle of cylindrical formtouching the side walls of the container but leaving draft-openings atthe angles of the container, said candle extending lengthwise of thecontainer from the cap to the bridge-piece, substantially as set forth.

3. In a formaldehyde-generator, the conrainer made as a tube of two ormore thicknesses of asbestos paper cemented together and provided with aperforated cap at one end and with an interior support for the candlenear the other end, substantially as set forth.

4. In a formaldehyde-generator, the con- 4o tainer made of two or morethicknesses of asbestes paper cemented together, and closed at one endby a cap of perforated sheet metal having points turned at right anglesto the body of the cap and secured between the layers of the asbestospaper, substantially as set forth.

5. In a formaldehyde-generator, -the container made in tubular form ofasbestos paper and provided with a perforated cap at 5o one end and witha metal bridge-piece connecting the walls of the container near-theother end and secured thereto, substantially as set forth.

6. A formaldehyde-generator having the asbestos side Walls A providedwith air-open ings a, the .perforated metal cap B, and thc metalbridge-piece, D, substantially as set forth.

This specification signed and witnessed this 6o 3d day of December,1901.

ROBERT W. JOHNSON.

Vitnesses:

EDWARD MORRIS, JNO. L. CARBERRY.

